The invention relates to a method for determining the filling capacity of tobacco, in which method a predetermined quantity of tobacco is filled into a volume of known cross-section, closed on one side by a movable plunger, and in which method the respective length of the tobacco column and the respective force acting on the tobacco via the plunger are measured as a function of time.
The filling capacity corresponds to the visco-elasticity and compressibility of tobacco. It can be defined as the volume which a given mass of tobacco occupies after being subjected to a certain pressure for a certain time. The filling capacity of tobacco is greatly dependent upon its temperature and moisture. As tobacco exhibits a marked relaxation behavior, a reproducible measurement of the filling capacity of tobacco is only possible using a process which is also precisely defined as regards time. The filling capacity depends on the type of tobacco and is an important characterizing variable for the evaluation of the tobacco quality.
A method and an apparatus for the determination of the filling capacity of tobacco are known from the article "Untersuchungen mit einem verbesserten Densimeter zum Pruefen der Fuellfaehigkeit von Schnittabak und der Haerte von Cigaretten", by H. W. Lorenz and F. Seehofer, Beitraege zur Tabakforschung, Volume 4, issue 7 (1968). To measure the filling capacity, about 20 g of tobacco are poured loosely into a cylindrical container ca. 60 mm. in diameter. If this container is placed in the known apparatus, a pressure plate on which a weight has been placed, sinks from above onto the tobacco. The position of the pressure plate and consequently the height of the tobacco column is transmitted to a dial gauge or another display device. After a preselected time, which is on the order of one minute, has passed, a motor automatically lifts away the pressure plate including the weight from the compressed tobacco and the final height of the tobacco column is displayed as a measure of the filling capacity.
Owing to the small size of the tobacco container, this method is limited to determining the filling capacity of cut tobacco when the known apparatus is used. The accurate measurement of a curve which represents the pattern of the final height of the tobacco column as a function of time is tedious because an individual measurement must be carried out for each time value. A further disadvantage is that the method only allows the filling capacity of tobacco to be determined by means of random samples with small amounts of tobacco. The temperature and the moisture, or the water-content, of the tobacco, which have a considerable effect on the filling capacity, cannot be measured directly in the known apparatus. The moisture, for example, must be determined separately using a drying chamber. The tobacco moisture can change during the lengthy filling capacity measurements or when the associated moisture determination is not carried out immediately before or after the measurement, which leads to a distortion of the results for the filling capacity.
The object of the invention is to provide a method of the type mentioned above for the determination of the filling capacity of tobacco, in which method the measurement of the filling capacity takes place completely so that it is not restricted to random samples and so that a certain tobacco quantity can in each case be allocated a filling capacity value. The filling capacity is to be measured with a high degree of accuracy in this method, taking into account the determining parameters. The method is to run automatically, and interruptions or delays to the normal procedure in the handling of tobacco are to be avoided. Furthermore, the method is to be inexpensive and able to be implemented without using expensive machinery.
To achieve this aim, the necessary measurement variables are acquired and processed automatically by at least one computer while the tobacco is being packed into packaging containers by means of a press, or during additional pressing by a press after packing, the length of the tobacco column being determined from the measured distance covered by a movable plunger of the press which compresses the tobacco and in doing so moves it into said packaging container, or which plunger performs the additional pressing of the tobacco, and the force acting on the tobacco being determined from the measured pressure required to drive said plunger, or from the measured supporting force required to hold said packaging container, or from the measured force occurring at said plunger or its drive elements, and additional parameters governing the value of the filling capacity are determined in independent measurements and fed into said computer which calculates filling capacity values therefrom.
In this way the quantity of tobacco packed into any given packaging container is assigned a reliable filling capacity value determined by means of a well defined, reproducible measuring process. This makes possible an uninterrupted testing of the quality of the tobacco.
A further object of the invention is to provide a method of the type mentioned initially for the determination of the filling capacity of tobacco which can be applied to leaf tobacco and which meets the other requirements mentioned above.
To achieve this aim the above described method is applied to leaf tobacco.
In this way the quantity of leaf tobacco packed into any given packaging container is assigned a reliable filling capacity value determined by means of a well defined, reproducible measuring method. This makes possible an uninterrupted testing of the quality of the leaf tobacco. Furthermore, the filling capacity value for the leaf tobacco can be correlated with the value for the filling capacity of the cut tobacco produced later from the leaf tobacco, so that conclusions can be drawn at this early stage about the expected quality of the cut tobacco, which hitherto was not possible and constitutes a great advantage for industrial production.
A further object of the invention is to define the method for the determination of the filling capacity of tobacco that informative data can be obtained for the filling capacity during clearly specified measurement processes.
This is achieved in that a compression curve is recorded in which curve the force acting on the tobacco during the compression is shown as a function of the length of the tobacco column, and in which curve the plunger speed is used as a parameter, and/or in that a relaxation curve is recorded in which curve the force acting on the tobacco is shown as a function of time, after the plunger has reached its end position and the compressed tobacco column has therefore reached its minimum length and while the plunger remains in its end position.
Through this means, curves are made available with data relevant for the filling capacity, from which one or more values can be taken to characterize an assigned filling capacity value.
Another object of the invention is an alternative implementation of the method such that only a few data which are necessary for the determination of a filling capacity value are determined.
This object is achieved by using, during the compression of the tobacco, only a single measurement point or a few measurement points for the force acting on the tobacco and the associated length of the tobacco column, and/or by using only a single measurement point or a few measurement points for the force acting on the tobacco as a function of time, after the plunger has reached its end position and the compressed tobacco column has therefore reached its minimum length and while the plunger remains in its end position.
While this means that not so many measuring points are available as are required for a complete compression curve and/or a complete relaxation curve, it makes the measuring method and the establishment of an assigned filling capacity value particularly simple.
Another object of the invention is to determine all the parameters governing the value of the filling capacity.
To achieve this object, the tobacco temperature and the tobacco moisture are measured before, during or after the compression of the tobacco. The mass of the tobacco filled in, as a parameter governing the measured values of the filling capacity, is determined by weighing.
The force acting on the tobacco is preferably measured simultaneously by several of the alternatives listed above. Using the data obtained, conclusions can, for example, be drawn on the frictional forces occurring during the compression of the tobacco, which must be taken into consideration as machine-specific disturbing factors in the evaluation of the data for the establishment of filling capacity values.
An apparatus for the implementation of the method for the determination of the filling capacity of tobacco consists preferably of a press, known per se, which compresses a predetermined quantity of tobacco by means of a driven, movable plunger, starting from a larger volume, into a packaging container; and on the press are provided a distance-measurement device for measuring the distance covered by the plunger, pressure and/or force-measurement devices for determining the force acting on the tobacco, and interfaces and at least one computer for the automatic acquisition and processing of these measured variables as well as others determined in independent measurements. The press can carry out the actual packaging of the tobacco, but can also be provided for an additional pressing of the tobacco when it is already in its packaging container before the packaging container is sealed.
In a preferred embodiment according to the present invention, there is provided a method for determining the filling capacity of tobacco wherein a predetermined quantity of tobacco is filled into a volume of known cross-section defined by a column, closed on one side by a movable plunger forming part of a tobacco press and on its other side by a support surface, comprising the steps of disposing the tobacco into the column onto the support surface, compressing the tobacco in the volume by relatively moving the plunger and support surface toward one another, determining the length of the tobacco column during relative movement of the plunger and support surface as a function of time by measuring the distance covered by the relative movement of the plunger and the support surface and providing an output signal responsive thereto, determining the force acting on the tobacco as a function of time when the tobacco is compressed in the column and providing an output signal responsive thereto, independently measuring at least one of temperature and moisture content of the tobacco and providing an output signal in response thereto and processing the signals by a computer to determine the filling capacity of the tobacco.
In a further preferred embodiment according to the present invention, there is provided apparatus for determining the filling capacity of tobacco comprising a press for compressing a predetermined quantity of tobacco including a column for receiving the tobacco and a movable plunger for movement within the column, a packaging container for receiving the lower end of the column and the quantity of tobacco in the column when compressed by the plunger, a distance measurement device for measuring the distance moved by the plunger when compressing the tobacco, a measurement device for determining the force acting on the tobacco during compression thereof and providing an output signal in response thereto, means for measuring at least one of the temperature and moisture content of the tobacco and providing an output signal in response thereto and at least one computer for processing the signals for determining the filling capacity.
These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings.